A means for instantaneously stopping the main cylinder of a card has long been sought for safety reasons. The great danger to operating personnel engendered by the rotation of the massive main cylinder clothed with wire teeth is well known to those skilled in the trade and it has heretofore been thought impossible to effect a relatively rapid or instantaneous stop. By instantaneous stop it is meant that the main cylinder may be stopped within about three seconds or in less time than it usually takes to create damage. By use of the apparatus of the present invention it is possible to stop the main cylinder before the hand or arm of the operator may become engaged in its teeth. To this end it is desirable that safety switches be provided operable by movement of a safety trip bar or lever, or by removal of covers, cover plates or doors and the like so that the main cylinder will be stopped before it becomes accessible to operational personnel.
While electric brakes and the like have been utilized in connection with certain textile carding and drafting aparatus such as illustrated in U.S. Pat. No. 3,530,542 such have proved to be impractical insofar as providing an instantaneous stop. Efforts to utilize electric brakes such as illustrated in the patent have proved to be impractical to create an instantaneous stop and are not serviceable over a long period of time. This is because by their nature they are concentrically mounted and a minimum of lever arm is afforded in order to create stopping torque.
Another advantage of an instantaneous stop is to make it possible to stop the various carding elements associated with or driven by the main cylinder quickly and in proportion so as not to cause the web to come down but rather to remain up so that carding may be resumed quickly. It would thus be possible to stop the card without having to put up the web each time when starting again. This would be of special advantage in stops over the weekend where the card may simply be restarted without having to put the ends up at the beginning of the week.
The instantaneous stopping apparatus is especially desirable for the use when conducting maintenance operations. During maintenance operations the card is blown down or cleaned by blasts of air in which case it is necessary to move the covers and perhaps the cleanout doors at the bottom of the frame. For safety reasons when clearing chokes, it is important that the main cylinder be stopped. This normally takes about ten minutes and operators have the tendency to become impatient and may not realize that the main cylinder is still rotating. Safety switches for actuating the braking mechanism of the invention may be placed in a number of locations such as on the doors and covers, as well as on the regular panel for the electrical circuitry. It is important that the braking mechanism be carried adjacent the main cylinder shaft on the side of the card.